A semiconductor body of a super junction FET (field effect transistor) includes a drift region with p-doped areas separated by n-doped areas, wherein the n-doped areas carry the on-state current for n-FETs and the p-doped areas carry the on-state current for p-FETs. In the reverse mode depletion zones extend between the p-doped and n-doped areas in a lateral direction such that super junction FETs accommodate a high reverse breakdown voltage at high impurity concentrations that provide a low on-state resistance.
In an unclamped inductive switching environment FETs directly switch off a current through an inductive load. The inductive load provokes an off-state current flowing through the FET until the energy stored in the inductive load has been dissipated. The induced current triggers an avalanche mechanism in the FET, wherein the electric field in the FET generates mobile charge carriers conveying the off-state current. Typically FET specifications specify a single-shot or repetitive avalanche ruggedness rating to allow for the design of electric circuits with safe operating conditions. It is desirable to provide super junction semiconductor devices with improved avalanche ruggedness.